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PubMedDate not supplied

[Determination of hydrocortisone in human blood plasma using competitive binding with endogenous transcortin].

A direct express-method is developed for estimation of hydrocortisone, based on the use of individual human blood plasma endogenous transcortine as a binding system. The method is designed for non-serial estimation of hydrocortisone in human blood plasma and may be used for an express-analysis, since extraction of the hormone from blood plasma by organic solvents is omitted. The dissociation constant of the transcortine-hydrocortisone complex was calculated using Scatchard plot. On the basis of this procedure and considering the rule of acting masses the initial concentration of receptor sites was measured for transcortine at a given blood plasma dilution and theoretical curves were constructed for the reaction of competitive substitution of labelled hydrocortisone by the unlabelled hormone. Estimation of hydrocortisone, carried out by means of these theoretical curves of substitution, closely correlated with the data of experimental standard curves of substitution (CEA-IRE-Sorin). The express-method of hydrocortisone estimation was used in clinical research.

Binding, Competitive↗
PubMed1981

[Comparative determination of transcortin, total cortisol and free cortisol in the plasma of mothers, newborn and non-pregnant women (author's transl)].

We determined plasma transcortin, total cortisol and free cortisol in mothers, new borns and nonpregnant women. The blood samples were drawn immediately upon delivery. The mothers had significantly higher levels of total cortisol as well as free cortisol and transcortin when compared to non-pregnant women. The new borns had higher levels of total cortisol and free cortisol but unchanged levels of transcortin in comparison to normal subjects. Significant differences were also found with respect to total protein and albumin in all groups.

Blood↗
PubMed1980

[Chromatographic transcortin analysis of the blood plasma in tumor-bearing rats].

The binding of 3H corticosterone was studied comparatively in partly purified preparations of blood plasma transcortin in intact and tumor-bearing rats at the 12th day after transplantation. By means of chromatography on DEAE-cellulose and hydroxylapatite transcortin was purified about 200 times. It was demonstrated that the content of bound 3H corticosterone in 1 mg of protein in blood plasma preparations from tumor-bearing animals is 3.5 times less than in the plasma of intact rats. The observed reduction of the transcortin binding capacity in the blood plasma of rats with Walker carcinosarcoma is retained also in purified preparations of the blood plasma tanscortin of tumor-bearing rats.

Adsorption↗
PubMed1976

[Studies on the changes of transcortin-level in patients with glaucoma (author's transl)].

Changes in the plasma transcortin level were studied in patients with primary glaucoma, glaucoma and diabetes, diabetes mellitus compared with a control croup. It was found that the plasma transcortin level of the patients with or without glaucoma was significantly higher than that of the control values. Moreover, the analysis of the dissociation constant of transcortincorticosterone complex revealed that it is greater in patients with primary glaucoma than could be expected by the dilution ratio. Further studies are required to understand the mechanism of the changes occurring in plasma transcortin level in glaucoma.

Corticosterone↗
PubMed1979

Inhibition of endogenous RNA polymerase activity from thymus chromatin by transcortin-hydrocortisone complex.

A transortin-hydrocortisone complex has been isolated from human serum by affinity chromatography on oxidized corticosterone coupled to AH-Sepharose 4B. The influence of this complex and of hydrocortisone alone on endogenous RNA polymerase activity from thymus chromatin have been tested. Results show that hydrocortisone alone has no effect on RNA polymerase activity from thymus chromatin. Under the same experimental conditions, The transcortin-hydrocortisone complex induces an important decrease in the incorporation of UMP into RNA. The dose response of thymic RNA polymerase to transcortin-hydrocortisone complex and the effects of alpha-amanitin on this response are also reported.

Amanitins↗
PubMed1977

Affinity labelling of human transcortin.

The binding site of transcortin has been studied by using bromoacetyltestosterone and bromoacetylated derivatives of progesterone which were monohydroxylated at different positions of the steroid nucleus. Specificity of affinity labelling was demonstrated by the displad cortisol analog was added to a [3H]cortisol-transcortin complex solution. The binding site crevice was found to be very narrow in the vicinity of the A and B rings of steroid since 2alpha-hydroxyprogesterone, 6alpha- or 6beta-bromoacetoxyprogesterone and dexamethasone could not displace bound cortisol. A specific affinity labelling was obtained with 11alpha-bromoacetoxyprogesterone, 16alpha-bromoacetoxyprogesterone and 17beta-bromoacetyltestosterone. The results of the affinity labelling by these hormone analogs suggested that one methionine and one histidine residues were located within the active site:methionine might interact with the 11beta-hydroxyl group and histidine with the 20 keto group of cortisol.

Affinity Labels↗
PubMed1982

Prednisolone binding to albumin and transcortin in the presence of cortisol.

The protein binding of prednisolone was assessed in a 5% albumin solution and in pooled human serum, alone and in the presence of various amounts of cortisol. Significant displacement of prednisolone from transcortin binding sites occurred with little or no change in transcortin binding capacity or affinity constant for prednisolone, suggesting competitive inhibition of prednisolone binding by cortisol. Little or no displacement of prednisolone from the protein binding sites on albumin occurred though a decrease in the number of binding sites (four vs two), and an increase in the affinity constant for the albumin-prednisolone interaction (4.32 X 10(2) vs 9.43 X 10(2) M-1) occurred in the presence of cortisol. Allosteric conformational changes may occur in albumin structure in the presence of cortisol. These alterations have no effect on the fraction of prednisolone bound to albumin.

Allosteric Regulation↗
PubMed1982

Vaginal administration of ethinylestradiol: effects on ovulation and hepatic transcortin synthesis.

Ethinylestradiol (EE) was given vaginally to circumvent the intestinal metabolism and initial liver passage which follow oral intake. This route of administration was chosen in an effort to enhance the antiovulatory potency of EE, while decreasing adverse hepatic reactions. Vaginal tablets containing 20-30 micrograms of EE were taken daily by 7 ovulating volunteers from day 5 to day 25 of the menstrual cycle. The regimen resulted in serum EE levels of 62 +/- 27 pg/ml (mean +/- S.D.) 8-10 hours after insertion. Ovulation was inhibited in 5 women (monophasic basal body temperature curves, serum progesterone levels of 0.9 +/- 1.1 ng/ml during the second half of the treatment cycle). The cortisol-binding capacity of transcortin was significantly elevated in all subjects (52.3 +/- 6.4 micrograms/100 ml; controls 25.7 +/- 2.2 micrograms/100 ml). These findings indicate that intravaginal EE is twice as potent as oral EE in regard to inhibition of ovulation as well as stimulation of the hepatic transcortin synthesis. Vaginal administration apparently increases the bioavailability of EE; it does not facilitate a selective reduction of estrogenic effects upon the liver.

Adult↗
PubMed1975

Prostatic cancer. Transcortin levels during treatment with estramustine phosphate.

Plasma transcortin and cortisol levels, which are significantly elevated by estrogens, were determinied in a group of patients with prostatic cancer who were on estramustine phosphate (Estracyt) therapy. In a series of 44 male patients studied transcortin and corticol levels became elevated above normal and were maintained at these high levels as long as the patients were on estramustine phosphate therapy. The levels observed in this study may serve as reliable indices to monitor patients who are on this drug.

Diethylstilbestrol↗
PubMed1981

Modulation by transcortin-like binding sites of uptake and distribution of glucocorticoids by dispersed pituitary cells.

The influence of transcortin-like (TL) binding sites on uptake and distribution of glucocorticoids by dispersed pituitary cells was investigated. TL material, which combines corticosterone (CORT), but not dexamethasone (DEX), was previously found to be present on cell membranes and in cytosol of hypophysis. Exposure of cells at 0 degrees brought about striking differences in steroid binding, as labeled CORT was taken up more rapidly and to a significantly greater extent than DEX. This resulted from a higher concentration of binding sites and not from a difference in binding affinity. At 25 and 37 degrees, while the same relationship was apparent during the early events of steroid interaction with the cell, binding of DEX increased gradually with incubation time and finally exceeded that of the natural steroid. Also, time-course studies on nuclear translocation showed a biphasic pattern, which closely paralleled that of whole-cell binding. Interestingly, treatment of rats with transcortin antiserum caused a decrement of pituitary TL sites, as well as of CORT translocation. We conclude that the TL binder, which is probably of plasma origin, may be actively involved in the process of uptake and cellular distribution of corticosteroids in the pituitary gland.

Animals↗
PubMed1982

Structural organization of the carbohydrate moiety of human transcortin as determined by methylation analysis of the whole glycoprotein.

Methylation analysis of human transcortin showed that this glycoprotein contains N-glycosidically linked oligosaccharide chains of N-acetyllactosamine type, most of the chains being biantennary and others tri- and/or tetra-antennary. The carbohydrate chains of transcortin are also heterogeneous with respect to the content of fucose and the position of the glycosidic linkages.

Carbohydrate Sequence↗
PubMed1975

[Characterization and physico-chemical properties of human transcortin].

The molecular weight of human transcortin, calculated from the sedimentation coefficient, was found to be 49,500, thus slightly lower than previously reported values. After purification, human transcortin trended to polymerize rapidly, with participation of both non covalent bonds and one disulfide bridge per dimer. The physicochemical parameters, the amino-acid and carbohydrate composition were determined; its stability was studied under different conditions. Preliminary structural studies showed that the N-terminal sequence of the polypeptide chain was: Met-Asp-Pro-Asn-Ala-Ala-Tyr-Val and that the C-terminal amino acid was leucine.

Amino Acid Sequence↗
PubMed1990

Cortisol-21-sulfate (FS) is a specific ligand for intracellular transcortin: demonstration of three types of high affinity corticosteroid binders in bovine aortic cytosol by a combined use of FS and RU 28362.

This paper reports the results of a study on the binding of adrenal steroids in bovine aortic tissue. Using the same method as in our previous study of mineralocorticoid and glucocorticoid binding in rabbit arterial cytosol, we could not demonstrate in the bovine aorta the three types of high affinity binders for these steroids, which we found in the rabbit arteries. In the search for specific markers for each of the three types of binders (glucocorticoid and mineralocorticoid receptors and the transcortin-like intracellular binder), we have found that a conjugated steroid, cortisol-21-sulfate, binds preferentially to the transcortin-like binder, but not to the two receptors. Using this steroid, in combination with the pure synthetic glucocorticoid RU 28362, we were able to clearly discriminate between the three types of corticosteroid binders in bovine aorta.

Adrenal Cortex Hormones↗
PubMed1976

Effects of ethinylestradiol on the renin-angiotensin-aldosterone-system and on plasma transcortin in women and men.

The effects of ethinylestradiol (1 mug/kg body weight daily) on plasma renin substrate concentration, other factors of the renin-aldosterone-system, and on the cortisol-binding capacity of transcortin were determined in 8 young men and 9 young women. The absolute and relative elevation of plasma renin substrate after 5, 14, and 24 days of ethinylestradiol administration was significantly (P less than 0.001) greater in females than males. Control and posttreatment transcortin levels were also higher in women than men, but the percentage increase did not differ between males and females. It is likely that sex differences in the response of plasma renin substrate to the estrogen are due to differences in hepatic synthesis and/or release of renin substrate. In females, plasma renin activity, angiotensin II concentration, and urinary aldosterone excretion rose significantly although less markedly than plasma renin substrate concentration, while in males only the increase in plasma angiotensin II concentration was significant. These results indicate that no safe conclusions on metabolic effects of estrogen treatment in women can be drawn from experiments carried out in male subjects.

Aldosterone↗
PubMed1977

The binding of a synthetic progestin, R5020 to transcortin and serum albumin.

R5020 (17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione), a synthetic progestin, was tested for its binding to purified human transcortin, albumin and human serum. Scatchard analysis showed that R5020 bound relatively weakly to transcortin (Kass = 8 X 10(6)M-1); in 20% human serum or albumin greater than 90% was bound with low Kass and an indeterminate number of binding sites.

Humans↗
PubMed1982

The serum concentrations of unbound, transcortin bound and albumin bound cortisol in patients with dysproteinemia.

Three cortisol fractions, protein-unbound (U-F), transcortin-bound (Tr-F) and albumin-bound cortisol (Al-F) were measured in patients with dysproteinemia by a newly devised isocolloidosmolar equilibrium dialysis method. Total cortisol (Total-F) concentrations in patients with liver cirrhosis (LC), anorexia nervosa (AN) and cachexia due to cancer (CA) were higher than in normal subjects, and those in patients with nephrotic syndrome (NS) and multiple myeloma (MM) remained within the normal range. In all groups of patients, the U-F concentration, which is believed to be the sole active fraction of cortisol, showed significantly higher values than in the normal subjects. We, therefore attempted to find which of the two binding proteins contributes to the elevated U-F concentrations. Concentrations of each cortisol fraction are greatly changed by alterations in the Total-F concentration. We therefore compared the Tr-F against Total-F and Al-F, and U-F against Total-E of patients with those of normal subjects. It was found that decreased transcortin-binding and not albumin-binding in the patients with cirrhosis, nephrotic syndrome and myeloma contributed to an increase in the U-F concentration. Although decreased binding of albumin due to hypoalbuminemia was found in LC, NS, MM, CA and AN, it had relatively little effect on cortisol distribution in the serum.

Anorexia Nervosa↗
PubMedDate not supplied

[The effect of epiphysectomy on the concentration of aldosterone, corticosterone and transcortin in the peripheral blood].

Experiments were conducted on female Wistar rats, weighing 120-130 g. Epiphysis in rats was removed 3 weeks before the principal experiment. Aldosterone was determined in the peripheral blood by the radioimmunological method, corticosteron--spectrophotometrically, binding capacity of transcortin, free, bound and sum-total 11-OCS--by the method of gel filtration in biogel. In intact rats at the phase of metaestrus aldosterone content in the peripheral blood constituted 45.2 +/- 4.62 ng/100 ml. Epiphysectomy produced a reduction of aldosterone content (32.4 +/- 3.69 ng/100 ml) and an elevation of corticosterone level and of transcortin binding capacity in the female rats.

Aldosterone↗